According to the drugs’ labels, the most common SGLT2 side effects are vaginal yeast infections, yeast infections of the penis, stuffy or runny nose, and changes in urination. These common side effects occurred in two percent or more of clinical trial participants.

Common SGLT2 side effects include:
  • Urinary tract infection
  • Female and male genital yeast infections
  • Upper respiratory tract infections
  • Increased urination
  • Dyslipidemia (increase in cholesterol)
  • Joint pain
  • Nausea
  • Thirst
  • Back pain
  • Constipation
  • Flu
  • Painful urination

While clinical trials show the most common side effects are relatively minor, FAERS shows the most reported adverse events are more serious. The top three most-reported events in FAERS are diabetic ketoacidosis — a condition where a lack of insulin causes acid to build up in the blood— fungal infections and kidney injuries.

In 2015, the FDA released a Drug Safety Communication warning about the risk of ketoacidosis — also called diabetic ketoacidosis — and serious urinary tract infections (UTIs). The agency required drug companies to add warnings to SGLT2 medication labels.

In the same communication, the FDA warned about the risk of urinary tract infections that could turn into life-threatening blood infections (urosepsis) and kidney infections (pyelonephritis). The agency identified 19 cases of blood and kidney infections that began as urinary tract infections.

In August 2018, the FDA released a Drug Safety Communication warning that SGLT2s may cause a rare but serious genital infection called necrotizing fasciitis of the perineum — also known as Fournier’s gangrene. The disease can be life-threatening. Symptoms include tenderness, redness or swelling of the genitals and fever.

From 2014 to Sept. 30, 2018, the FDA received reports of 41 cases of bladder cancer and bladder neoplasms (possible cancerous growths) in people who took Farxiga (dapagliflozin). One person died.

In 2017, the FDA required Johnson & Johnson and Janssen Pharmaceuticals to add a black box warning to Invokana, Invokament and Invokamet XR for lower limb amputations. The agency based its decision on the results of two large, randomized, placebo-controlled trials that found amputations occurred twice as often in people who took canagliflozin versus a placebo, according to the FDA’s Drug Safety Communication. 

The FDA urges people who suffer from leg or foot pain or tenderness, sores or ulcers, or infections to contact their doctor. From 2016 to Sept. 30, 2018, the agency received 236 reports of amputation in people who took Invokana. Two cases resulted in death.

In 2016, the FDA warned medications containing canagliflozin and dapagliflozin may harm kidneys. The agency required the drugs’ makers to strengthen warnings on the medication inserts.

From March 2013 to October 2015, the FDA identified 101 reported cases of kidney injury in users of canagliflozin and dapagliflozin. Some people needed to be treated in the hospital with dialysis. About half of these cases occurred within one month of starting either of the drugs.

More recent FAERS data shows people reported 1,614 cases of kidney injury with all SGLT2s from 2013 to Sept. 30, 2018 — including 54 deaths.